In the past year, the battle over UNIX has generated significant litigation and lots of anxiety among the open source community and software users alike. However, the multi-front battle is complex, making it hard to understand what's going on and what's at stake. This article explains the disputes, summarizes the latest status (as of 6/14/04), and offers some possible lessons to learn.

SCO v. Well, Almost Everybody

The battle involves UNIX, a computer operating system. The term UNIX describes a family of software products that conform to certain common standards promulgated by the Open Group. The "original" version of UNIX was developed by Bell Labs in 1969. Since then, the efficiency and reliability of UNIX have made it a very popular operating system, spawning a wide variety of compatible versions. For example, IBM has a version of UNIX called AIX, which traces its lineage to the original Bell Labs software. Another UNIX-compatible program is Linux, an open source project that includes some code contributed from AIX by IBM.

In 2003, Caldera Systems, Inc., doing business as The SCO Group (hereafter just "SCO"), announced that it was going to assert ownership over the original Bell Labs version of UNIX source code and all derivations of it. SCO's claims sent shockwaves through the software community. Given UNIX's ubiquity, SCO's claims potentially affect anyone using AIX, Linux, and other variations of UNIX.

Indeed, SCO has sparked a war over UNIX, which has resulted in four interrelated lawsuits:

The war started when SCO sued IBM for providing AIX to the open source community to enhance Linux.

In response to SCO's lawsuit against IBM, Novell declared that it had some rights to the UNIX code, which raised questions about SCO's ownership of the UNIX code. SCO responded by suing Novell for publicly disparaging SCO's title to UNIX.

Realizing that SCO's claims threatened its business (and spooked its customers), Red Hat, a software vendor that markets a Linux version, sued SCO for a declaratory judgment of non-infringement, and asserted that SCO's ownership claim misleads Linux consumers.

Finally, SCO recently took its claims to their logical conclusion by suing two end users of Linux and AIX: AutoZone and DaimlerChrysler.

The war over UNIX has divided the software industry in two. The anti-SCO forces include IBM, Novell, Red Hat, and the open source community. The open source community has been particularly active in challenging SCO's claims, generating evidence to contradict the claims and raising money for a legal defense fund for Linux users.

However, some software industry participants have sided with SCO. A prominent ally is Microsoft, which appears to have helped SCO raise $50 million by introducing SCO to a funding source called BayStar Capital. Although SCO recently bought out that investment, the buyout left SCO with a substantial war chest. Microsoft's interests in the matter may result from the strong competitive threat that Linux has posed to Microsoft's own software programs.

This article summarizes the events associated with the battle over UNIX. First, we discuss the chain of title to the UNIX code. Second, we summarize the various litigations and the software community's response to SCO's efforts. Finally, we point out some lessons that might be learned from these battles.